在本研究中，我們結合了多重解析度地形模塑、視點相關展示及動態載入等技術做飛行模擬應用。以多重解析度的技術來展示地形模型的意義是在增進視覺效果而不減少視覺品質的要求下，讓每個地形區塊各自擁有變動的解析度，而且解析度會自動根據螢幕空間誤差 (screen space error) 作調整。一般來說，把一大塊地形模型載入到記憶體做展示是不切實際的。因此，我們將大區域地形模型切割成許多矩形小地塊，並且動態地載入所需的小地塊到記憶體中展示；而且每個地形區塊都有視點相關多重解析度模塑 (view-dependent multiresolution modeling) 的功能。 在飛行模擬的應用中，飛行器可能會靠近或遠離地形模型，而視野範圍也就跟著改變。為了進一步增進視覺效能及品質，我們讓地形區塊數量可以隨著視點高度自動改變。然而，在只有一個處理器的電腦上執行飛行模擬時，當載入地形區塊時，飛行瀏覽常會被暫停。為了消除這個現象，我們依據最近的飛行方向來預測飛行路徑，然後利用處理器執行的空檔預先載入可能需要的地形區塊。除了展示地形，地面上有許多建築物，我們以離散多重解析度模塑技術來塑造建築物，以提升展示的速度並增加場景的真實性。 Terrain scenery visualization is the key topic of this study. In a practical terrain visualization system, the amount of terrain data is always huge. In such a case, it is generally impractical to load the whole terrain model into the main memory. So, we need to partition a large terrain model into small blocks and then dynamically load the necessary terrain blocks into the memory for rendering. To improve the visualization performance without reducing the visual quality, every terrain block has its own variant resolutions and the variable resolution is automatically adapted based on the screen-space error. That is, every terrain block possesses the view-dependent multiresolution modeling function. In addition to the terrain models, many buildings are constructions and also included in the scenery. To improve the rendering performance, the buildings and constructions are also built as multiresolution style. Moreover, we add the prediction of flying path for increasing the visual efficiency and the quality of the terrain scenery for the application of flight simulation. Google Earth is an excellent commercial multiresolution terrain visualization system. Google Earth has been extended to combine daily information of living. We have all similar techniques as Google Earth. In the future, we will extend our system to browse the whole Taiwan to detailedly describe the beautiful Taiwan as Google Earth.
